Alternative method for determination of ceftazidime in plasma by high-performance liquid chromatography

Simultaneous determination of ceftazidime and pyridine in human plasma by LC-UV

A sensitive, accurate and precise liquid chromatography (LC) method for the simultaneous determination of ceftazidime and pyridine in human plasma has been developed and validated. Acetonitrile (ACN) was employed to precipitate the proteins in the plasma samples. Chromatographic separation was performed with a Kinetex® C18 (150 mm × 3 mm, 2.6 µm) column with gradient elution. Ammonium formate 20 mM and ACN were mixed in a ratio of 98:2 (v/v) for mobile phase A and 85:15 (v/v) for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was 0.4 mL/min. UV detection was performed at 254 nm. Calibration curves were linear in the range from 0.3 to 225 μg/mL for ceftazidime and from 0.2 to 10 μg/mL for pyridine with correlation coefficients ≥ 0.999. Within- and between-run precision and accuracy were satisfactory with coefficients of variation (CV) ≤ 8.0% and deviations ≤ 7.0%, respectively. The method fulfilled all validation criteria prescribed by the European Medicines Agency guidelines. Next, it has been used successfully to analyze plasma samples of patients who received ceftazidime under intermittent and continuous administration. With intermittent administration, the concentration of the antibiotics reached a peak and then dropped quickly, which may be below the minimal inhibitory concentration (MIC). With continuous administration, the concentration of the antibiotics remained stable over 24 h, certainly above the MIC. Although the same tendency in ceftazidime concentration changes over time was observed, a difference in concentration amongst the patients was noticeable. The concentration of pyridine in plasma was negligible.

Determination of ceftazidime in plasma by RP-HPLC and ultraviolet detection

A simple high-performance liquid chromatography method for the determination of ceftazidime in plasma has been developed. Using an ultrafiltration technique samples were separated by reverse-phase high-performance liquid chromatography on a Symmetry C₁₈ 4.6 × 250 mm column (5.0 μm) and ultraviolet absorbance was measured at 260 nm. The mobile phase was a mixture of 10 mm potassium phosphate monobasic pH 2.5 with phosphoric acid and acetonitrile (90:10). The standard curve ranged from 0.1 to 100 μg/ml. Intra- and inter-assay variability for ceftazidime was <12%, and the average recovery was 89%. The lower limit of quantification was 0.1 μg/ml. This method has been used successfully to analyze frog plasma samples at this institution and it could be applied to other small volume samples in a clinical or research setting.

Population pharmacokinetics of continuous-infusion ceftazidime in febrile neutropenic children undergoing HSCT: implications for target attainment for empirical treatment against Pseudomonas aeruginosa

OBJECTIVES

To conduct a population pharmacokinetic analysis of continuous-infusion ceftazidime in a retrospective cohort of paediatric HSCT patients who were empirically treated for febrile neutropenia (FN) and who underwent therapeutic drug monitoring of ceftazidime steady-state plasma concentrations (Css) for optimization of drug exposure.

METHODS

A non-parametric approach with Pmetrics was used for pharmacokinetic analysis and covariate evaluation. Monte Carlo simulations were performed to calculate the PTA of the pharmacodynamic determinant of efficacy (Css/MIC ≥4) against Pseudomonas aeruginosa with continuous-infusion ceftazidime dosages of 1-6 g daily. The Css safety threshold was arbitrarily placed at 100 mg/L and advisable dosages were used.

RESULTS

A total of 46 patients with 70 ceftazidime Css values were included. Estimated glomerular filtration rate (eGFR) and body surface area were the covariates associated with drug clearance. At the EUCAST clinical breakpoint of 8 mg/L, simulations showed that continuous-infusion ceftazidime dosages of 4-6 g daily attained optimal PTAs (>90%) across most of 16 different clinical scenarios based on four classes of eGFR (50-145, 145.1-200, 200.1-286 and 286.1-422 mL/min/1.73 m2) and body surface area (0.30-0.64, 0.65-0.88, 0.89-1.34 and 1.35-1.84 m2). In patients with body surface area 0.30-0.64 m2 and eGFR ≤200 mL/min/1.73 m2 the advisable dose of 3 g daily allowed only suboptimal PTAs (<75%). The cumulative fraction of response against MIC distribution of P. aeruginosa was >87%.

CONCLUSIONS

Continuous-infusion ceftazidime dosages ranging from 3 to 6 g daily according to different classes of eGFR and body surface area may allow optimized empirical treatment of P. aeruginosa infections in paediatric HSCT patients with FN.

Development and validation of spectrophotometric methods for determination of ceftazidime in pharmaceutical dosage forms

Two spectrophotometric methods for the determination of ceftazidime (CFZM) in either pure form or in its pharmaceutical formulations are described. The first method is based on the reaction of 3-methylbenzothiazolin-2-one hydrazone (MBTH) with ceftazidime in the presence of ferric chloride in acidic medium. The resulting blue complex absorbs at lambdamax 628 nm. The second method describes the reaction between the diazotized drug and N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to yield a purple colored product with lambdamax at 567 nm. The reaction conditions were optimized to obtain maximum color intensity. The absorbance was found to increase linearly with increasing the concentration of CFZM; the systems obeyed the Beer's law in the range 2-10 and 10-50 microg mL-1 for MBTH and NEDA methods, resp. LOD, LOQ and correlation coefficient values were 0.15, 0.79 and 0.50, 2.61. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, sensitive, accurate and suitable for quality control applications.

Analysis of cephalosporin antibiotics

A comprehensive review with 276 references for the analysis of members of an important class of drugs, cephalosporin antibiotics, is presented. The review covers most of the methods described for the analysis of these drugs in pure forms, in different pharmaceutical dosage forms and in biological fluids.

Disposition of Ceftazidime After Intraperitoneal Administration in Adolescent Patients Receiving Continuous Cycling Peritoneal Dialysis

BACKGROUND

Peritonitis is the single most common complication in children maintained on continuous cycling peritoneal dialysis (CCPD) and a significant cause of morbidity. Recent consensus guidelines for the treatment of peritonitis in children receiving peritoneal dialysis recommend the combined intraperitoneal administration of ceftazidime with either a first-generation cephalosporin or vancomycin. The objective of this study is to determine whether a continuous maintenance dose of intraperitoneal ceftazidime in the absence of a loading dose would maintain adequate serum and dialysate concentrations to be effective in the treatment of peritonitis.

METHODS

Five ambulatory patients on CCPD therapy were studied with continuous intraperitoneal administration of ceftazidime (125 mg/L). Blood, dialysate, and urine samples were collected at specified intervals during a 24-hour period. Ceftazidime concentrations were measured by using a high-performance liquid chromatography assay.

RESULTS

Mean serum concentrations at completion of the short rapid cycles and at 24 hours were 28.92 +/- 13.64 and 23.92 +/- 11.93 microg/mL, respectively. Serum bioavailability at 24 hours was 74% +/- 6%. Mean dialysate concentrations at completion of the short rapid cycles and at 24 hours were 87.43 +/- 19.18 and 32.06 +/- 6.27 microg/mL, respectively. All 5 patients achieved serum and dialysate ceftazidime concentrations greater than the mean inhibitory concentration within 4 hours.

CONCLUSION

In adolescent patients on CCPD therapy, a continuous maintenance dose of intraperitoneal ceftazidime in the absence of a loading dose achieves serum and dialysate levels greater than the mean inhibitory concentration of sensitive organisms within 4 hours that persist for 24 hours.

Ceftazidime in acute myeloid leukemia patients with febrile neutropenia: helpfulness of continuous intravenous infusion in maximizing pharmacodynamic exposure

The pharmacokinetic-pharmacodynamic profile of a fixed 6-g daily continuous intravenous infusion of ceftazidime was assessed in 20 febrile neutropenic patients with acute myeloid leukemia. Mean steady-state ceftazidime concentrations averaging 40 mg/liter from day 2 on ensured maximized pharmacodynamic exposure (values close to four to five times the MIC breakpoint against Pseudomonas aeruginosa). However, large intra- and interindividual pharmacokinetic variability was documented throughout the study period.

Determination of ceftazidime in plasma and cerebrospinal fluid by micellar electrokinetic chromatography with direct sample injection

A simple micellar electrokinetic chromatography (MEKC) with UV detection at 254 nm for analysis of ceftazidime in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of ceftazidime from biological matrix was performed at 25 degrees C using a background electrolyte consisting of Tris buffer with sodium dodecyl sulfate (SDS) as the electrolyte solution. Under optimal MEKC condition, good separation with high efficiency and short analyses time is achieved. Several parameters affecting the separation of the drug from biological matrix were studied, including pH and concentration of the Tris buffer and SDS. Using cefazolin as an internal standard (IS), the linear ranges of the method for the determination of ceftazidime in plasma and in CSF were all over the range of 3-90 microg/mL; the detection limit of the drug in plasma and in CSF (signal-to-noise ratio = 3; injection 0.5 psi, 5 s) was 2.0 microg/mL. The applicability of the proposed method for determination of ceftazidime in plasma and CSF collected after intravenous administration of 2 g ceftazidime in patients with meningitis was demonstrated.

Aerosolized ceftazidime for prevention of ventilator-associated pneumonia and drug effects on the proinflammatory response in critically ill trauma patients

STUDY OBJECTIVES

To evaluate the safety and efficacy of aerosolized ceftazidime for prevention of ventilator-associated pneumonia (VAP) and to evaluate the effects of the drug on the proinflammatory response.

DESIGN

Prospective, randomized, double-blind, placebo-controlled clinical trial.

SETTING

University teaching hospital.

PATIENTS

Forty critically ill trauma patients at high risk for VAP Intervention. Within 48 hours of admission to the intensive care unit (ICU), patients were randomly assigned to receive aerosolized ceftazidime 250 mg every 12 hours or placebo (normal saline) for up to 7 days. Bronchoalveolar concentrations of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-8 were determined at baseline and the end of therapy (days 4-7).

MEASUREMENTS AND MAIN RESULTS

The frequency of VAP in patients receiving aerosolized ceftazidime was 73% lower than that in patients receiving placebo at ICU day 14 (15% vs 55%, p = 0.021), and 54% lower for the entire ICU stay (30% vs 65%, p = 0.022). No clinically significant changes in bacterial culture and sensitivity patterns were observed. No adverse events from aerosolized ceftazidime were reported. Pulmonary TNF-alpha, IL-beta, and IL-8 concentrations were attenuated in the ceftazidime group compared with those in the placebo group (p < 0.001, p = 0.02, and p = 0.003). The frequency of VAP was related directly to changes in TNF-alpha and IL-beta (p < 0.001, p = 0.02).

CONCLUSIONS

Aerosolized ceftazidime decreased the frequency of VAP in critically ill trauma patients, without adversely affecting ICU flora. Aerosolized ceftazidime also may attenuate the proinflammatory response in the lung.

Measurement and pharmacokinetic analysis of unbound ceftazidime in rat blood using microdialysis and microbore liquid chromatography

To evaluate the biodisposition of ceftazidime in rat blood, a rapid and simple microbore liquid chromatographic technique together with a microdialysis sampling technique were developed. This method involves an on-line design for blood dialysate directly injected into a microbore liquid chromatographic system. The chromatographic conditions consisted of a mobile phase of methanol-acetonitrile-100 mM monosodium phosphoric acid (pH 3.0) (10:10:80, v/v/v) pumped through a microbore reversed-phase column at a flow-rate of 0.05 ml/min. With the detection wavelength set at 254 nm, a good linear correlation was observed between the peak area and the ceftazidime concentration at 0.1 to 50 microg/ml (r=0.999). Microdialysis probes, being custom-made, were screened for acceptable in vivo recovery while chromatographic resolution and detection were validated for response linearity, as well as intra-day and inter-day variabilities. This method was then applied to the pharmacokinetic profiling of ceftazidime in blood following intravenous 50 mg/kg administration to rats. The pharmacokinetics was calculated from the corrected data for dialysate concentrations of ceftazidime versus time. This method has been used to study ceftazidime pharmacokinetics in rats and has proven to be rapid and reproducible.

Intermittent and continuous ceftazidime infusion for critically ill trauma patients

BACKGROUND

The adequacy of intermittent and continuous infusion ceftazidime for the treatment of nosocomial pneumonia in critically ill trauma patients was assessed by analyzing ceftazidime pharmacokinetics in relation to the minimum inhibitory concentration (MIC) and treatment outcome.

METHODS

Serial blood samples were obtained during ceftazidime therapy in 31 trauma patients. Ceftazidime pharmacokinetics were compared with that of previously studied healthy volunteers. Ceftazidime pharmacokinetics were analyzed according to the time above the MIC and treatment outcome.

RESULTS

Critically ill trauma patients had a significantly increased volume of distribution and clearance (0.32 +/- 0.14 L/kg and 2.35 +/- 0.89 mL. min(-1). kg(-1), respectively) compared with healthy volunteers (0.21 +/- 0.03 and 1.58 +/- 0.23 mL. min(-1). kg(-1)). The time above the MIC was >/=92% of the dosing interval for all patients and treatment outcomes were similar between the two treatment groups.

CONCLUSIONS

Ceftazidime pharmacokinetics are significantly altered in critically ill trauma patients. Both intermittent and continuous ceftazidime regimens were equally effective for the treatment of nosocomial pneumonia caused by less virulent bacteria.